1. Technical Field
The disclosure relates to a receiver device, and more particularly to a device and a method for Non Return to Zero (NRZ) Clock Data Recovery (CDR) calibration.
2. Related Art
FIG. 1 shows the architecture of an ordinary communication system, which includes a transmitter 101, a channel 102 and a receiver equalizer 103. The receiver equalizer 103 includes an equalization filter 110 and a CDR unit 120. The equalization filter 110 is used for receiving a channel signal VX and compensating the channel signal VX to obtain a compensative signal X, and the CDR unit 120 is used for receiving the compensative signal X and outputting a data signal Z and a sampling clock signal CLK.
If the CDR unit 120 in the prior art adjusts the sampling clock signal CLK without considering data dependence during data transition, a correct CLK may be adjusted to be an incorrect CLK, and the CLK adjustment may be slowed down. Moreover, when the channel signal VR suffers serious interference, the equalization filter 110 cannot fully compensate the channel signal VR, so that the compensative signal X is incomplete, and if the CDR unit 120 receives the incomplete compensative signal X, serious offset or loss-of-lock occurs to the phase and the frequency of the CLK of the CDR unit 120. At this time, when the equalization filter 110 receives the normal channel signal VR and generates the compensative signal X, the CDR unit 120 in the prior art still repeatedly uses the phase and the frequency of the offset CLK to sample the compensative signal X and obtain sampling data, and a logic operation unit in the CDR unit 120 uses the sampling data for operation to gradually obtain the phase and the frequency of the normal CLK step by step, but cannot quickly adjust the CLK. When the circuit in the CDR unit 120 causes serious offset or loss-of-lock of the CLK due to noise interference, the CDR unit in the prior art cannot quickly calibrate or adjust the phase and the frequency of the CLK even if the CDR unit returns to normal condition.